This invention relates to an apparatus useful in handling elongated well elements such as pipe, tubing, and sucker rods and, more particularly, the invention relates to a mobile, totally contained and automatically operated servicing and drilling rig for use in oil well or other similar operations.
In oil well operations, elongated well elements such as tubing, pipe and sucker rods are used for such purposes as well production and well drilling. Individual well element sections are connected together to form an elongated segmented string for use in the well. The segmented string frequently comprises of the order of a hundred or more well elements.
A rig hoist is used to lower each successive section into the well to approximately its full length. After the section has been lowered to such a position, it is gripped near its upper end by suitable means, such as slips, to suspend it in the well. The hoist is then released from this section and a second section is supported from the hoist and then coupled to the first section. The second section is then lowered into the well to its full extent, and it is then held by the slips and the above sequence repeated. As this sequence is repeated, successive sections form a string which progressively goes deeper and deeper into the well.
If such a string is being removed from the well the hoist is connected to the uppermost section and the entire string is lifted until such section clears the well. The remaining string is hung by the slips in the wellhead and the uppermost section is then uncoupled and moved to a storage position. In the usual prior art field operations, the storage position is adjacent to the wellhead and sections, are transported from the storage position to the wellhead for connection to the hoist or removal therefrom by manual means. In other prior art systems separate mechanical conveying elements are required to operate the hoist and to transport the sections from the storage position to the hoist position.
In much of the prior art operations, several operators are required to perform all of the functions that are necessary to place a section into the hoist position, to connect or disconnect it from the string, and to run the string into the well or to remove it from the well. In some cases, this has required an operator at the wellhead level, an operator at an elevated position above the wellhead to connect or disconnect the sections from the hoist, and an operator to place the sections in the storage or to remove them from the storage position. Each of the operators involved in the operation of running well elements into and out of a well is in intimate contact with the wellhead and with the elements removed from the well.
Many of the petroleum wells today operate at elevated temperatures, either because of their depths within the earth formation or because of their operation in secondary recovery systems where steam or hot fluids are pumped into the well to cause the heavier crudes to become more mobile so as to flow toward the producing wells. In the treatment and operation of such wells, the removal of well elements becomes more difficult because of their elevated temperature. In some cases wells are cooled for many days through the procedure of pumping cold water into the well to bring the elements to a temperature where they may be safely handled by personnel. Automatic well element handling apparatus have been proposed to handle such elements so as to avoid the cooling step necessary to bring the element to a temperature where individuals may touch them.